The September 8, 2026, release of the updated 45ZCF-GREET model and accompanying IRS guidance delivered a major development for the biofuels industry: regenerative agriculture is now being integrated into the 45Z Clean Fuel Production Credit framework, along with dairy and swine manures being added to the 2026 emissions rate table.
Please find some of the updates below and make sure to review our documents for a full summary.
45z IRS guidance
The IRS guidance introduces a Safe Harbor for 2025 and 2026 feedstocks, recognizing that many crops were planted before USDA’s final guidance was released. As such, for fuel produced in 2025 and 2026, the requirements regarding the pre-application development of a nutrient budget, are deemed satisfied for purposes of § 45Z.
Dairy manure and swine manure are now included as primary feedstocks in the 2026 emissions rate table. Please note, *The IRS anticipates that poultry and beef manures will be added in a future update and to await subsequent 45ZCF-GREET model updates, rather than submitting a PER.
Christianson’s Summary of Guidance on Establishment of Emissions Rates and Regenerative Ag for the 45Z tax credit
changes in the 45Z DOE model
The release marks a significant step toward rewarding lower-carbon agricultural practices throughout the fuel supply chain while providing additional certainty for early adopters.
- Incorporates the 45Z FD-CIC to be used for calculating intensity adjustments for feedstocks produced using regenerative agriculture practices
- Renames ‘Distillers Corn Oil (DCO)’ to ‘Distillers Corn Oil/Distillers Sorghum Oil (DCO/DSO)’ to clarify that this feedstock may be either or a blend of both
- Updates categories for imported used cooking oil (UCO) as a feedstock in 2025 to align with most recent clarifications regarding 45Z eligibility
- For certain pathways (ethanol), the model adds user inputs for facilities operating integrated natural gas combined heat and power (CHP) systems for on-site electricity production and now allows facilities the ability to offset those electricity emissions by purchasing environmental attribute credits (EACs)
- Added pathway for Renewable Natural Gas (RNG) from food scraps, corn stover, grain stillage and high-moisture organic wastes via anaerobic digestion and upgrading
Christianson’s Summary of Updated 45ZCF-GREET Model Changes
Important Links and Further Reading
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